Padlocks are used in a variety of applications, including, for example, with enclosures such as lockers, storage sheds, and various gates and doors, to secure two or more hasps, latches or other structures together to restrict access to an item or enclosure. A conventional padlock includes a shackle having two ends secured within a lock body by one or more locking members when in a locked condition, with the locking members being disengageable from the shackle in the unlocked condition to allow movement of the shackle to separate one end (or leg) of the shackle from the lock body. Some padlocks include key operated arrangements in which insertion of a proper key in a keyway permits rotation of a key cylinder to release or disengage one or more locking members from the shackle. Other padlocks include a combination (or permutation) dial operable to rotate a series of cams to an unlocking orientation, in which the cams permit disengagement of one or more locking members from the shackle.
One conventional padlock includes a sliding latch that is secured in engagement with a corresponding notch in the shackle when the padlock is locked. When the padlock is unlocked, the latch is slidable out of engagement with the shackle recess to permit withdrawal of a short leg of the shackle from the lock body. One example of such a padlock is shown in FIGS. 1A through 1C, and is described in U.S. Pat. No. 3,990,275 (the “'275 patent”), the entire disclosure of which is incorporated herein by reference, to the extent that it is not conflicting with the present application. As shown in FIGS. 1A-1C, the combination padlock of the '275 patent includes a pivotable lever or rocker 23 that receives a slidable latch or latch bolt 24 for locking engagement with a corresponding notch 25 in the shackle 27. When the rocker 23 is in a first orientation (corresponding with the locked condition), as shown in FIG. 1A, the latch 24 is prevented from retracting into the rocker 23 and out of engagement with the shackle recess 25, by full engagement of the latch nose 48 with the notch 25, and interference between the latch shoulder 51 and the front edge of the recess 35 in the rocker 23. When the combination dial is rotated to the proper series of positions, slots 40 in a series of tumbler disks align with an extension or tongue 39 of the rocker 23, thereby permitting the rocker 23 to pivot to a second orientation (corresponding with the unlocked condition). In this second orientation, the latch 24 becomes disengaged from the shackle recess 25, such that the short leg 26 of the shackle 27 may be withdrawn from the lock body or lock casing 10 to unlock the padlock. To re-lock the padlock, reinsertion of the short leg 26 of the shackle 27 into the lock body causes the short leg 26 to cam against the latch nose 48, retracting the latch 24 into the rocker 23 to permit full insertion of the shackle 27. When the shackle recess 25 is realigned with the latch nose 48, spring 37 forces the latch 24 back into locking engagement with the shackle recess 25.
Other examples of padlocks with similar locking arrangements are described in U.S. Pat. Nos. 2,893,231 and 4,422,311, the entire disclosures of both of which are incorporated herein by reference, to the extent that they are not conflicting with the present application.
Whether combination dial operated, key operated, or both, padlocks having a slidable latch for engaging and disengaging the shackle may be vulnerable to unauthorized opening of the lock (and access to the locked item, structure, or enclosure with which the lock is used) by tampering with the latch. For example, a slidable latch may be manipulated using a shim, pick, or other such tool or device inserted between the shackle and the edge of the shackle hole in the lock body. Additionally or alternatively, the shackle of this type of padlock may be rapped or otherwise impacted to move the latch with respect to the shackle, in an effort to disengage the latch from the shackle.